Probably time to do a repair install.
This won't affect your personal stuff or 3rd party installed programs but you will need Win 10 install media.
You can get that from this website but read the instructions as they differ depending upon whether you want to use a DVD or USB.
If using a DVD, it will save the ISO to your Docs folder.
https://www.microsoft.com/en-gb/software-download/windows10When done, open Windows Explorer and This PC - insert the media and double click on its drive.
If using a DVD that will normally start the process, whereas if you are using an USB, that will open its files where you would double click on setup Application.
There is a little user input but for the most part it will just get on with it.